( Reaffirmed 2004 ) IS:8201-1976 Indian Standard SPECIFICATION FOR HIGH FREQUENCY WIDEBAND MATCHING TRANSFORMER Transformers Chairman SRRI R.S. MUNDEUR Members SREENIVAS ( Alternate to Shri R. S. Mundkur ) All India Radio &_Electronics Association, Bombay SHRI H. K. L. ARORA SHRI R. G. KESWANI ( Alternate ) ( Bombay ) SHRI ARUP CFUUDHURI ( Alternate ) ( Calcutta ) Electronics Corporation of India Ltd, Hyderabad SHRI R. P. BARETI SRRI B. S. RAO ( Alternate ) Electronic Component Industries Association, New SHRI G. V. DESAI Delhi National Test House, Calcutta SHRI B. P. GHOSH Indian Telephone Industries Ltd, Bangalore KUMARI K. R. JAYA SHRI DAVID ( Alternate ) The Radio Electronic and Television Manufacturers. SHRI R. K. JAIN Association ( RETMA ), Bombay SHRI T. J. DHABHAR ( Alternate ) Philips India Ltd, Bombay SHRI R. R. JEUSIWAL.~ SHRI M. M. JOSEI ( Alternate ) DIRECTOR STANDARDS Railway Board ( Ministry of Railways ) JOINT (S&T) DEPUTY DIRECTOR STANDARDS ( S & T ) ( Alternate ) The Development Commissioner, Small Scale SHRI B. MAJTJB~DAR Industries, New Delhi Posts & Telegraphs Department SHRI M. N. MATHUR Civil Aviation Department ( Ministry of Tourism & SHRI N. K. NANU Civil Aviation ), New Delhi SHRI VISHWANATH ( Alternate ) Ministry of Defence ( R & D ) LT CDR N. REDDY Directorate General of Supplies & Disposals SHRI M. SANKARALIN~AM SHRI G. R. BHATIA ( Alternate ) and Inductors for Electronic Equipment Committee, LTDC 8 Rejrcsenting Bharat Electronics Ltd, Bangalore Sectional SHRI C. K. ( Continued on Page 2 ) IS I 8201.1976 I( Continuedfrom #age 1 ) Members SHRI Representing Physical Laboratory ( CSIR ), New Delhi Research Development Corporation of India, DeIhi General, ISI ( Ex-o#cio Member ) National National New SHRI M. P. BRATNA~AR ( Alternate ) Director SHRI N. SRINIVA~AN,. Director ( Electromcs ) P. SURYANARAYAN SHRI C. G. SUBRAMANIAN Secretaries SHRI M. N. RADHAERISHNA Assistant Director ( Electronics ), ISI SHRI S. C. GUPTA Assistant Director ( Electronics ), IS1 Indian Standard SPECIFICATION FOR HIGH FREQUENCY WIDEBAND MATCHING TRANSFORMER 0. FOREWORD 0.1 This Indian Standard was adopted by the Indian Standards Institution on 7 September 1976, after the draft finalized by the Transformers and Inductors for Electronic Equipment Sectional Committee had been approved by the Electronics and Telecommunications Division Council. 0.2 This standard lays down the methods of test and general require-ments applicable to high frequency (hf) wideband impedance matching transformers used for balanced to unbalanced coupling and impedance transformation, in electronic and telecommunication equipment. These transformers are commonly known as baluns. 0.3 This standard is one of a series of Indian Standards on transformers and inductors for electronic equipment. A list of standards so faxpublished in this series is given on page 18. 0.4 It is recognized that in the case of components like wideband matching transformers, the performance requirements are related to thedesign of the particular circuit for which they are intended and it would, therefore, be difficult to lay down specific values for all characteristics independent of the equipment design. The intending purchaser should, therefore, furnish details of additional requirements of the component.. A list of items for which the purchaser should specify the requirements. is given in Appendix A. 0.5 This standard requires reference to IS : 589-1961* as far as the details of the climatic and mechanical testing procedures are concerned. Only the relevant degrees of severity have been specified in this. standard. 0.6 In the preparation the following: JSS of this. standard assistance has been derived from 54680 General specification for matching transformers ( balun ). Directorate of Standardisation, Department of Defence Production, Ministry of Defwce. and mechanical durability tests for electronic components ( reuised )_ -c--o - *Basic climatic 3 IS : 8201.1976 MIL-T-28732B( Department MIL-T-28767( Department EC ) Transformer, of Defence, USA. EC ) Transformer, of Defence, USA. impedance impedance matching matching (balun). ( balun ). 0.7 For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test, shall be rounded off in accordance with IS : 2-1960". The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. -1. SCOPE 1.1 This standard lays down the methods of tests and general requirements applicable to high frequency ( hf) wideband impedance matching transformers ( baluns ) used for balanced to unbalanced coupling and electronic and telecommunication impedance transformation, in "equipment. 1.1.1 The transformers covered are meant for operation over frequency range I.5 to 30 MHz having unbalanced impedances between 50 and 75 ohms or balanced impedances between 50 and 600 ohms. 1.2 The matching transformers covered include: for transmitting systems for feeder sources and loads over and a) high power matching transformers matching balanced or unbalanced a w.ide range of impedance ratios, b) low power matching transformers for receiving systems for matching balanced antenna and unbalanced transmission lines over a wide range of impedance ratios. 2. TERMINOLOGY the purpose of this standard, the following definitions shall 2.0 For apply. carried out to prove conformity with the 2.1 Type Tests -Tests They are intended to prove the general requirements of this standard. qualities and design of a particular type of transformer. -Tests carried out on samples of transformers 2.2 Acceptance Tests selected from a lot for the purpose of accepty;ce of the lot. *Rules for rounding off numerical values ( revised ). 4 . -c-w : I 1st 8201.-1976 2.2.1 Lot - All transformers of the same grade and rating manufactured by the same factory during the same period. 2.3 Routine Tests - Tests carried out on each transformer the requirements which are likely to vary during production. 3. CLIMATIC CATEGORIES AND TYPES to check 3.1 Climatic Categories - The hf transformers shall belong to one of the following three categories based on their ability to withstand the climatic severities: Climatic Test (See IS : 589-1961* ) Severity -,-h---_-_--r~ r--Category 1 Category 2 +loo"c -55°C 56 days 6 cycles +looOc to -55°C 44 mbar +85"C -40°C 56 days 6 cycles +85"C to -40°C 300 mbar Category 3 +70°c - 10% 21 days 2 cycles Not applicable 600 mbar ) and Dry heat Cold Damp heat ( long term .) Damp heat ( accelerated ) Rapid change of temperature Low air pressure NOTE 1 - A recovery period of 24 hours after the damp heat ( accelerated damp heat ( long term ) tests is necessary for Category 3 components. NOTE 2 - In special cases where the above categories are not applicable other combinations of severities may be agreed to between the purchaser and the manufacturer provided such severities are chosen from IS : 589-1961*. 4. RATINGS 4.1 The power ratings in kW should be chosen from RlO series ( see IS : 1076-1967t ) given below, the italicized values being preferred: I, 1.25, 1.6, 2'0, 2'5, 3.15, and sub-multiples. 5. MATERIALS, 5.0, 6.3, 8.0 or their decimal multiples CONSTRUCTION AND WORKMANSHC P 5.1 Materials-The transformer shall be constructed from materials As far as practicable, materials used free from flaws and other defects. for construction shall be nonflammable, nonexplosive and noncorrosive. . *Basic climatic and mechanical durability tests for elea&onic components TPreferred numbers ( jirst revision ). ( revised ). 118: 8201- 1976 5.2 Construction 5.2.1 The principal features include hermetic sealing to withstand severe environmental conditions, simple mounting arrangements, small size and weight and oil-filled construction in the case of high power transformers. 5.2.2 The windings, internal wiring and assembly in the housing shall be rigid and secure so that intermittent contact due to vibration shall not occur during transportation or use. Suitable coaxial connectors to match the impedance and power handling capacity and to meet environmental requirements shall be used. The balanced terminals shall be of ,suitable type and size and at spacings as required ( see Appendix A). An external grounding termination shall be provided on the transformer if required. The housing should be such as to provide shielding against stray electromagnetic fields and to preclude stray radiation from the Each of the balanced terminals shall be provided with -transformer. lightning protection if required. 5.2.3 Oil-filled units shall be filled with suitable oils and shall be ensured to be leak-free in any position. They may be provided with -suitable gaskets and oil level indicators if required. The enclosure should be such that with oil to the correct level there shall be an air space at the top to absorb expansion of oil or increase in internal The enclosure shall be constructed entirely of aluminium, cast pressure. ,or welded. They shall stand an internal pressure of 250 kPa and have a leakage rate of 0'000 04 cma/s at 100 kPa. Enclosures of transformers sof rating higher than 10 kW ( average ) shall be provided with suitable .h andles to facilitate handling. 5.3 Finish i Unless otherwise specified, all exposed materials liable to deterioration in moist or other corrosive atmosphere shall be given suitable finish. .5.4 Workmanship - All parts of the transformer shall be manufactured in a thoroughly workmanlike manner and in accordance with good engineering practice. 6. MARKING 6.1 Each transformer shall be clearly and indelibly following: 4 Manufacturer's name or trade-mark; marked with the b) Manufacturer's code/type number; 4 Terminal identification with impedances; 4 Power and frequency range; and . J4; 4 Any other markirrg, such as batch `number, drawing, etc, manufacturer. as agreed to between 6 the date, schematic purchaser, and the %c1. - 6.2 In addition to the marking specified in 6.1, the following information shall be supplied in form of a detailed specification sheet along with the units: a) Insertion b) Insertion c) Permissible d) Symmetry e) `Connectors loss, VSWR ( voltage standing VSWR, winding, terminals, and wave ratio ), load mismatch of balanced used, mounting position. f) Spacing between balanced g) Recommended 7. TESTS 7.1 Classification of Tests 7.1.1 Type Tests - accordance The procedure for type with that given in IS : 2612-1965*. approval shall be irn 7.1.1.1 transformer required. 7.1.1.2 accordance .Number of samjdes -The manufacturer shall submit o ne, of each type and power rating for which type approval is Sequence of type tests - The sequence of type tests shall be in. with the following order: ( 7.4.1 ) , ), a) General tests 1) Visual examination 2) Dimensions ( 7.4.2 3) Mass ( 7.4.3 4) Continuity ), of winding ( 7.3.1), 5) DC resistance of winding ( 7.3.2 ), 6) Polarity ( 7.3.5 ), and 7) Insulation resistance ( 7.3.6 ). b) Terformance tests ( eledrical ) ratio (7.3.4), ( 7.3.7 ), ( for traqsmitter . d`! transformers ) winding ( 7.3.8 ), 1) Primary inductance ( 7.3.3 ), 2) Transformation 3) Low level inserti,on VSWR 4) Symmetry of balanced 5) Insertion loss or efficiency ( 7.3.10 ), *Recommendation for type approval and sampling procedures for .electronic -4.. components. ,* 7 3s t 8201.1976 6) Power and ( 7.3.11), 7) Overload load VSWR (7.3.12), (where specified) (where (7.3.13), and and specified) products applicable ( for transmitter transformers) VSWR 8) Spurious frequencies 9) Intermodulation ( 7.3.14 ). c) Environmental tests 1) Vibration (7.4.5), 2) Shock (7.4.6), 3) Climatic ( 7.5), 4) Salt mist ( 7.5.7), 5) Mould growth (7.5.9), 6) Solar radiation (7.5.8). and acceptance tests as given in Table 1 shall 7.1.2 Acceptance Tests -The be carried out on limited number of samples selected in accordance with the sampling procedure given in IS : 2612-1965* and on those which have passed the routine tests. TABLE SL No. (1) TESTS (2) 1 ACCEPTANCE TESTS KG (3) INSPECTION I.EVEL (4) Transformers i) ii) for Transmitters : 1 1 1 percent II Dimensions ( 7.4.2 ) Mass ( 7.4.3 ) Spurious frequencies ( 7.3.13 ) Insertion loss/efficiency ( 7.3.10 ) Power and load VSWR ( 7.3.11 ) J for Receivers 71 4 percent s.3 iii) iv) v) Transformers vi) vii) viii) ix) Dimensions ( 7.4.2 ) Mass ( 7.4.3 ) Insertion loss/efficiency ( 7.3.10 ) i Intermodulation products ( where I specified ) ( 7.3.14 ) J ,-`_ *Recommendation components. for type approval and sampling procedures 8 _- for electronic . -4. I I . IS : 8201- 1976 following shall constitute the routine tests: 7.1.3 Routine Tests -The a) Visual examination ( 7.4.1), b) Continuity of winding ( 7.3.1), c) DC resistanceof winding (7.3.2), d) Primary inductance ( 7.3.3), ratio (7.3.4), e) Transformation f) Polarity ( 7.3.5 ), 8) Insulation resistance ( 7.3.6 ), h) Low level insertion VSWR ( 7.3.7), j) Symmetry of balanced winding (7.3.8), and ( 7.3.9 ). k) Power test (routine ) ( for transmitter transformer) 7.2 General Conditions for Tests 7.2.1 Tests shall be carried out on the transformers as received from the manufacturer or the supplier. 7.2.2 Atmospheric Conditions for TestingUnless otherwise specified, all tests shall be carried out under standard atmospheric conditions specified in IS : 589-1961*. 7.2.3 Preconditioning - Before measurements are made, the transformers shall be stored at the measuring temperature and relative humidity, for a time sufficient to allow the entire transformer to reach these conditions. The ,recovery period called for after conditioning is tidequate for this purpose.' ' ' are made at an 7.2,4 Correction to be<.Applied - When measurements ambient temperature other than the reference temperature, the results The shall, where necessary, be corrected to the reference temperature. ambient temperature during the tests shall be stated in the test report. 7.2.5 Other Precautions - During measurements, the transformers shall not be exposed to draughts, direct sunrays or other influences likely to cause errors. 7.3 Electrical Tests 7.3.1 Continuity of Winding - Each winding of the transformer shall be tested for electrical continuity by any suitable method. Each winding shall be continuous. 7.3.2 DC Resistance of Winding - The transformer shall be maintained under normal atmospheric conditions and the dc resistance of each winding shall be measured, the ambient temperature being simultaneously Unless otherwise specified, the value shall be referred to the recorded. temperature of 27°C and this value shall .be within the tolerance limits specified in the relevant Indian Standard. . d`! . *Basic climatic and mechanical durability_ tqts for electronic components"( &cd i ). I 9 ,' `L-7 r IS I 0201.1976 primary inductance shall be measured 7.3.3 Primazy Inductance -The The values shall be as specified at the specified frequency and voltage. in the relevant Indian Standards. transformation ratio of the transformer 7.3.4 Tranrjormation Ratio -The shall be computed from the ratio of voltages measured across the required winding with the secondary open-circuited, at the specified frequency and voltage the measurement being done with a high impedance voltmeter. The values shall be as specified in the relevant Indian Standards. 7.3.5 Polarity -Where suitable method. The Indian Standard. applicable, the polarity shall be checked by a polarity shall be as specified in the relevant 7.3.6 Insulation Resistance - Unless otherwise specified, the insulation resistance shall be measured by applying a dc test voltage of 500 V for one minute f5 seconds between the case and each winding, and between windings. 7.3.6.1 The insulation unless otherwise specified. resistance shall be not less than 1000 Ma Low Level Insertion VSWR - The impedance at the input terminals properly terminated transformer shall be measured by a bridge or Each measured value shall be normalized and equivalent method. The test shall be conducted at 1'5, 2, 4, 6, 9, plotted on a Smith chart. 12,15, 18, 28, 30 MHz for acceptance tests and 1.5, 2, 4, 9, 18, 28, and 30 MHz for routine test. The values shall be as specified in the relevant Indian Standards or 2 from 1.5 to 3 MHz range and 1.2 from 3 to 30 MHz. of the 7.3.7 two balanced terminals 7.3.0 S'inmetry of Balanced Winding -The associated with ground system is considered as a three terminal system with direct admittances r,, Tz and 2-3 involved (Fig. 1 ). G _* FIG. 1 ADMITTANCES ASSOCIATED WITH'~~'~ALANCED TERMINALS TO BE CONNECTED TO A LINE . Y-4*" _* 10 IS:8201-Z916 Three measurements are made as follows: electrode A 4 The admittance Y between electrode B grounded, The admittance circuited, and admittance Y' between and ground with with AB short- b) A and ground The c> Y"' between B and ground with A grounded. give: Y' = ri + r, Y' = Y, + Ts 11, r = r1 + Ts These measurements Solving for Yi, 2'+,and Y, gives: r= 2 Y+r.-Y" 2 L This enables to calculate following equation: Degree of symmetry the degree of symmetry given by the = 20 loglo r, _ T3 dB The values shall be as s+$ified in the relevant Indian Standard. 7.3.9 Power Test ( Routine) -L'For the purposes of routine testing only, the power test shall consist of that described in 7.3.10 and 7.3.11 except that the duration of test shall be until thermal stability is reached ( rather than 24 hours ), and ambient temperature is to be the uncontrolIed prevailing ambient temperature ( rather than 65 f 2°C ). 7.3.10 Insertion Loss/E#cien&~ (for Tranformers for Transmitters efficiency of the transformer shall be measured as given below: ) - The a) The output of the transmitter shall be connected to the input of the transformer. The balanced terminals shall be terminated with the specified matching resistive load. Full average power shall be applied at the input end. Ambient and transformer oil temperatures shall be recorded at half-hour intervals. Stabilization shall be taken as having been achieved":&hen temperature-rise is less than 1°C per half hour. . -4. ,' 11 IS : .a201 - 1926. b) RF power shall be de-energized. The transformer temperature shall `be, allowed to decrease to room ambient 27 f 2°C. A suitable heating element having heat density not exceeding 3'1 W/ems, shall be inserted into the transformer and shall be connected to a variable voltage source without changing physical set-ups. Power shall be applied to the heating element until the temperature of oil is stabilized to the same temperature 10'5°C as achieved in (a). The power input in (b) shall be equal to the power loss in (a). The efficiency shall be calculated as: Efficiency where Pin = input power, and Pout = output power. = e P = Pin (a) - Pin (b) x 100 Pin (a> The efficiency of the transformer shall be verified at 1'5, 2, 4, 6, 9, 15, 20,28 and 30 MHz or at any other frequency necessary to establish performance throughout the 1'5 to 30 MHz range. The efficiency of the transformer shall be 97 percent or better unless otherwise specified and the temperature-rise shall be within the specified limits. 7.3.11 Power and Load VSWR (for Transformers for Transmitters ) -The transformers which have passed insertion loss/efficiency tests and have obtained thermal stability will be tested for power and load VSWR. The transformer shall be tested with full ( average and PEP ) power applied over an uninterrupted 24 hour period at the most critical frequency determined by the efficiency tests with a 2'5 : 1 load VSWR or as specified. The transformer shall not be exposed to fans or forced draughts during test periods. Ambient temperature shall be 65 f 2°C. There shall be no evidence of arcing, any deterioration or leakage of oil. With a load VSWR of up to 2'5 : 1 or as specified the power handling capability of the transformer shall not be derated below full power. 7.3.12 Overload VSWR-The transformer shall be subjected to a VSWR of 4 : 1 or higher as specified for a period of 20 minutes at full power. There shall be no damage when the transformer is subjected to overload which results from this test. 7.3.13 Spurious Frequencies -The signal level of spurious frequencies generated in the transformer as a result of signal distortion or other causes shall be at least 60 dB below its full power rating or as specified. This level shall be measured at the output of th%d$ransformer with any load with VSWR of up to 2'5 : 1 and unbalanced up to 25 percent with respect to ground. : \-*. 12 ,* 18:8201-1976 The transformer shall be operating at rated power on each of the frequencies, which are 3, 4, 6, 9, 15, 20, 28 and 30 MHz. The transformer output shall be analyzed between 0.5 and 500 MHz ( excluding the operating frequency) or to check compliance with the requirements specified. 7.3.14 Intermodulation Products - The second and third order intermodulation products present at an output of a multicoupler system, when two 0.25 V rms signals at frequenciesf, and fi ( in the frequency range of the multicoupler in such a relationship that the second order product frequency equal to fi f f2 and the third order product frequency equal to 2 fi &fi falls within the specified range of the multicoupler and outside its range from O-1 MHz to 60 MHz ) are applied to its input, shall be at least 60 dB below either of the input signals. Measurements shall be made at the approximate frequencies specified Variations in these frequencies shall be permitted if necessary to below. Only one output avoid spurious responses in the measuring equipment. circuit need be measured provided it may be demonstrated that all outputs are identical. AI1 measurements shall be made with the input filter in the circuit, unless otherwise stated: fi f2 (fl +f, 1 > (2fl +f2 1 (.fl"ffZ ( 2fi0f- fi) MHz 2.1 3'5 3'5 5.6 75:; 7.7 11.2 11.2 15.4 21.0 3.5 2.2 15'4 30.0 21.0 ;:; MHz ;:o" 5.0 8.0 8.0 11.0 11.0 16.0 16.0 22.0 30.0 3-o 3.0 22.0 21.0 30.0 ;:; MHz + + + + + + + _t 5.1 1.5 8.5 13.6 2.4 18.7 3.3 27.2 4.8 6.6 9.0 0.5 0.8 37.4 51'0 51.0 0.4 0:3,; MHz + + + + + + + + + 7.2 2.0 12.0 19.2 3.2 26.4 4.4 6.4 53'4 8.8 12'0 10.0 1.4 52.8 39.0 72.0 1*7* l-l* : *To be performed with input filter by-passed. 13 %_W - IS : 8201-l&3 7.4 Physical and Mechanical Tests 7.4.1 Visual Exatiination - The transformer shall be visually examined for compliance with the relevant requirements of 5 and 6. 7.4.2 Dimensions - The dimensions of the transformer shall be checked and they shall conform to those specified in the relevant Indian Standard. shall be checked 7.4.3 Mass - The mass of the transformer compliance with those stated in the relevant Indian Standard. 7.4.4 Enclosure Mechanical Strength - for Under consideration. 7.4.5 Vibration -The transformer shall be mounted as specified in 7.6.4 of IS : 589-1961* taking care that no parts are stressed and the sample shall be subjected to vibration (fatigue) test in accordance with 7.6.6 of IS : 589-1961*. The transformer shall be in nonoperating condition during the test and shall be capable of normal operation immediately after the tests are completed. After the test, the transformer shall be visually examined and there shall not be any damage or deterioration. The continuity of the winding shall be checked. The inductance of the transformer and low level insertion VSWR, shall be measured and shall conform to the value specified in the relevant Indian Standard. 7.4.6 Shock - The transformer shall be mounted as specified in 7.6.4 and shall be subjected to shock test in accordance with 7.5.2 of IS : 5891961*. The transformer shall be in nonoperating condition during the test and shall be capable of normal operation immediately after the tests are completed. The severity and the duration of the test shall be as indicated in the relevant Indian Standard. At the conclusion of the test, the transformers shall be visually examined and checked for continuity of winding. There shall be no loosening of parts or other mechanical damage. 7.5 Climatic Tests 7.5.1 Dry Heat - The transformer shall be subjected to the dry heat The temperature of the test in accordance with 7.2 of IS : 589-1961". test chamber shall be maintained at the maximum category temperature of the transformer. The transformer shall be,*on full load during the .i ! exposure, if specified. *Basic climatic and mechanical durability tests for electronic cornponentrygctid & 14 IS t 8201- 1976 After recovery, the transformer shall be visually examined for any damage or deterioration. The continuity of winding, low level insertion VSWR and insulation resistance shall be measured and they shall be within the limits specified. 7.5.2 Damp Heat (Accelerated) (First Cycle) - The transformer shall be subjected to the first cycle of the damp heat ( accelerated ) test in accordance with 7.4 of IS : 589-1961*. The duration of the recovery shall be la hours. After recovery, the transformer shall be visually examined for any damage or deterioration. 7.5.3 Cold Test - The transformer shall be subjected to the cold test in The temperature of the chamber accordance with 7.1 of IS : 589-1961*. shall be maintained at the minimum category temperature of the transformer. The duration of recovery period shall be 14 hours. After recovery, the transformer shall be visually examined for any damage or deterioration. The continuity of winding, low level insertion VSWR, and insulation resistance shall be measured and they shall be within the limits specified. 7.5.4 Low Air Pressure -The transformer shall be subjected to low air pressure test in accordance with 7.12 of IS : 589-1961*. The pressure shall be appropriate to the category and the duration shall be 5 minutes. The transformer shall be in nonoperating condition during the test and shall be capable of normal operation immediately after the test. The continuity of winding, low level insertion VSWR, and insulation resistance shall be measured and they shall be within the limits specified. 7.5.5 Damp Heat ( Accelerated) ( Remaining Cycles ) - The transformer shall be subjected to the remaining number of cycles of damp heat ( accelerated ) in accordance with 7.4 of IS : 589-1961*. After recovery of 14 to 2 hours for Categories 1 and 2 transformers and 24 hours for Category 3 transformers, the transformers shall be The continuity of visually examined for any damage or deterioration. winding, low level insertion VSWR, and insulation resistance shall be measured and they shall be within the limits specified. 7.5.6 Rapid Change of Temperature - The transformer shall be subjected to rapid change of temperature test in accordance with 7.14 of IS : 589The number of cycles shall be one unless otherwise specified. 1961*. After recovery, the transformers shall be visually examined for any damage or deterioration. The continuity of winding, low level insertion VSWR, and insulation resistance shall be measured and'they shall be within the limits specified. . i'! *Basic climatic and mechanical durability tests for electronic components ( revised ). . .c1* I 15 ,* IS:8201-1976 transformer shall be subjected to salt mist test 7.5.7 Salt Mist -The in accordance with 7.10 of IS : 589-1961*. The duration of exposure shall be 4 days. After cleaning and recovery, the transformer shall be visually The continuity of winding, examined for any damage or deterioration. low level insertion VSWR, and insulation resistance shall be measured and they shall be within the limits specified. 7.5.8 Solar Radiation -The transformer shall be subjected in accordance with IS : 2106 (Part XVII)-1973T. to this test After recovery transformer shall be visually examined for any damage or deterioration. The continuity of winding, low level insertion VSWR, and insulation resistance shall be measured and they shall be within the limits specified. 7.5.9 Mould Growth -The transformer shall be subjected growth test in accordance with 7.9 of IS : 589-1961". to mould At the end of the test the transformer shall be visually examined for any damage or deterioration. The continuity of winding, low level insertion VSWR, and insulation resistance shall be measured and they shall be within the limits specified. *Basic climatic and mechanical durability tests for electronic components ( revised ). tEnvironmenta1 tests for electronic and electrical equipment: Part XVII Simulated . solar radiation at ground level. k-v " ,* 16 I§ : 8201- 1976 APPENDIX ( Clause 0.4 ) INFORMATION A TO BE GIVEN BY THE PURCHASER wideband impedance matching on the following items as are A-l. The purchaser of high frequency transformers shall furnish information applicable: Power a> and voltage insertion levels; b) Maximum cl Size; 4 Source and e) Turns ratio f> The lowest loss or minimum efficiency; load impedances; or the desired ratio of impedances; and highest operating frequencies and number of dB down with respect to the frequency. For certain applications, shape of the amplitude response is to be specified; d h) 3 k) Either the permissible ripple, that is, the fluctuation of amplitude in the pass band or whether the response is to be flat; The slope or rate of attenuation Minimum attenuation if any, beyond cut-off; in the stop band; and the amount of repel, to in the stop band and When fidelity of wave shape is important, specify the following: it may be necessary 1) Nature 2) of the generator ( for example, transistor, electron tube), its power capability or level, the class of operation ( for example, A, AB, B) and the degree of unbalance BC; of the loaded transformer at Variation in input impedance low and high frequencies; 3) Maximum 4) Maximum core; 5) Whether phase shift in the pass band; harmonic feed-back distortion is employed, contributed by the transformer of feed-back; if so, the amount the transformer 6) Whether loop and the permissible is inside or outside the feed-back phase shift in the stop band; and source or load . ,* .-r7 is " especially whq`the 7) Circuit ( schematic), nonlinear or the circuit is complicated.' 17 INDIAN ON STANDARDS TRANSFORMERS IS : 1512-1969 2612-1965 AND INDUCTORS FOR ELECTRONIC EQUIPMENT Tests and revision ) general requirements for IF transformers and RF coils (first Recommendation equipment for type approval and sampling procedures for electronic 6297 ( Part I )-1971 Transformers and inductors ( power, audio, pulse and switching ) for electronic equipment: Part I General requirements and tests 6297 ( Part II )-1973 Transformers and inductors ( power, audio, pulse and switching ) for cIectronic equipment: Part II Power trasformers. 6297 ( Part III )-I974 Transformers for electronic equipment: 6297 ( Part IV )-1974 Transformers for electronic equipment: 8201.1976 High frequency wideband and inductors ( power, audio, pulse and switching ) Part III Audio frequency transformers and chokes and inductors ( power, audio, pulse and switching Part IV Pulse and swrtching transformers matching transformer )